What is it about Albania that makes it such a popular hiding place (Voldemort, Helena Ravenclaw) and holiday destination (Quirrell, Bertha Jorkins) for British wizards? It would not be so strange in any separate case, but Albania just pops up too often in the series.

Here is a theory I really like from SuperCarlinBrothers, but it looks like it's not supported by canon.

I know there is a similar question: Why flee to Albania? - but I feel like it does not cover the subject.

UPD: I was asked to summarize the SuperCarlinBrothers theory for those who are not up to watch it. So in short, the point is that in the times of Helena Ravenclaw there was not such country as modern Albania yet, so she would hardly tell Riddle she fled to Albania. So maybe she meant something else by Albania? And then there is this wiki article that tells us Albania may refer to Scotland. Scotland instead of Albania makes more sense in many ways (watch the video for more info).

Ravenclaw, the Dark Lord, and Quirrell had connected reasons.

Though it’s true that four people choose to go to Albania, it’s not a coincidence for three of them. Helena Ravenclaw, the Dark Lord, and Quirrell all have connected reasons for going to Albania. Before she’d died and become the Grey Lady, Helena Ravenclaw chose to hide the diadem in Albania, which directly caused the Dark Lord to go there when she told him where to find it, and the Dark Lord hiding there then directly caused Quirrell to go. The only one who seems truly to have coincidentally visited Albania was Bertha Jorkins, who went there on vacation.

First, years ago Helena Ravenclaw hid herself and the diadem in Albania.

The first person to go to Albania was Helena Ravenclaw, who hid with the diadem in a forest there.

“A hollow tree?’ repeated Harry. ‘What tree? Where was this?’

‘A forest in Albania. A lonely place I thought was far beyond my mother’s reach.”
_{^{- Harry Potter and the Deathly Hallows, Chapter 31 (The Battle of Hogwarts)}}

She chose it since it was a secluded place and she thought her mother wouldn’t be able to find her.

The Dark Lord only used Albania because he’d found the diadem there.

The Dark Lord first went to Albania because the Grey Lady told him that’s where the diadem was.

“So Voldemort had managed to wheedle the location of the lost diadem out of the Grey Lady. He had travelled to that far-flung forest and retrieved the diadem from its hiding place, perhaps as soon as he left Hogwarts, before he even started work at Borgin and Burkes.”
_{^{- Harry Potter and the Deathly Hallows, Chapter 31 (The Battle of Hogwarts)}}

Then, when the Dark Lord needed a place to hide years later, he returned to those same woods.

“And wouldn’t those secluded Albanian woods have seemed an excellent refuge when, so much later, Voldemort had needed a place to lie low, undisturbed, for ten long years?”
_{^{- Harry Potter and the Deathly Hallows, Chapter 31 (The Battle of Hogwarts)}}

The Dark Lord’s reason for choosing Albania was directly because Helena Ravenclaw had first.

Quirrell went to Albania since he deliberately sought out the Dark Lord.

In the JKR Pottermore writing on Professor Quirrell, she stated he purposely sought the Dark Lord.

Quirrell set out deliberately to find whatever remained of the Dark wizard, partly out of curiosity, partly out of that unacknowledged desire for importance. At the very least, Quirrell fantasised that he could be the man who tracked Voldemort down, but at best, might learn skills from Voldemort that would ensure he was never laughed at again.
_{^{- Professor Quirrell (Pottermore)}}

Therefore, it wasn’t a coincidence that he went to Albania, where the Dark Lord was rumored to be.

Bertha is the sole ‘coincidence’ - but might’ve gone to see family.

The only one whose reason to go to Albania wasn’t connected to the others’ was Bertha Jorkins, who chose to go on vacation there. This doesn’t necessarily mean that Albania is a popular vacation spot - Bertha may have chosen it because she had family living there she wanted to visit.

“She definitely arrived in Albania, because she met her second cousin there. And then she left the cousin’s house to go south and see an aunt … and she seems to have vanished without trace, en route.”
_{^{- Harry Potter and the Goblet of Fire, Chapter 24 (Rita Skeeter’s Scoop)}}

Bertha has at least both a second cousin and an aunt living in Albania, as she goes missing on the way from her second cousin’s to her aunt. Because she has some family living there, Bertha would have a reason for wanting to go to Albania that other wizards wouldn’t necessarily share.

Quirrel wasn't only in Albania.

Harry’s first Defence Against the Dark Arts teacher is a clever young wizard who took a ‘Grand Tour’ around the world before taking up his teaching post at Hogwarts.
_{^{-Professor Quirrell - Pottermore}}

To me at least Grand Tour implies more than one visiting spot. So, he may have thought it was a major landmark (a.k.a it was his opinion) that he ought to visit on his Grand Tour before coming to Hogwarts to teach. Also, he might have made this part of his tour to find the remains of Voldemort.

Quirrell set out deliberately to find whatever remained of the Dark wizard, partly out of curiosity, partly out of that unacknowledged desire for importance. At the very least, Quirrell fantasised that he could be the man who tracked Voldemort down, but at best, might learn skills from Voldemort that would ensure he was never laughed at again.
_{^{- Professor Quirrel - Pottermore}}

Helena was simply hiding from her mother.

"He tracked me to the forest where I was hiding. When I refused to return with him, he became violent. The Baron was always a hot-tempered man.
_{^{- Harry Potter and the Deathly Hallows, Chpater 31 (The Battle of Hogwarts)}}

To me this quote implies several things: First, that she didnt consider Albania anything special (seeing as she refers to it as "The Forest") but probably thought it secluded and out of the way. Also, this is not certain but since Helena had traveled such a long way, from Scotland to Albania i would think that she had used other hiding spots along the way, and that she had thought that she had traveled far enough and would either be captured, or not found.

Bertha was there by coincidence.

She was simply on vacation in Albania, there are no apparent connected reasons.

Voldemort was there (at first) because that's were Helena hid the Diadem.

“So Voldemort had managed to wheedle the location of the lost diadem out of the Grey Lady. He had travelled to that far-flung forest and retrieved the diadem from its hiding place,
_{^{- Harry Potter and the Deathly Hallows, Chapter 31 (The Battle of Hogwarts)}}

Later he returns to those same woods because he thought them a good place to hide.

“And wouldn’t those secluded Albanian woods have seemed an excellent refuge when, so much later, Voldemort had needed a place to lie low, undisturbed, for ten long years?”
_{^{- Harry Potter and the Deathly Hallows, Chapter 31 (The Battle of Hogwarts)}}