Hogwarts is a place where you feel like pretty much anything can happen…because, well, it probably can. To offer just a few examples, you might find:
Ghosts roaming the halls (that's, like, in every HP installment), including one who just frequents the bathrooms (that would be Moaning Myrtle)
A magical goblet that spits out the names of the students who have been selected to compete in the Triwizard Tournament
A face in the fireplace (that's how Sirius appears to Harry so they can "meet" about strange happenings at Hogwarts)
A magical staircase that leads to the headmaster's office
A magical dish called a "Pensieve" that can hold your old thoughts/memories
And seriously, that's just a sample. This is a story of witches and wizards, so we're not totally surprised at how many kooky things are about in Hogwarts but…yeah, maybe the bathroom ghost was a little unexpected.
In any case, bottom line: Hogwarts is where all the "magic" happens. Like, literally.