Whenever I hear this, I feel a shiver down my spine. I've heard the same from a lot of people. Here it is, Beethoven's "Fur Elise":
https://www.youtube.com/watch?v=_mVW8tgGY_w
Apparently, when he was composing this piece, halfway through he found out that the woman he loved, had married someone else. Beethoven hit the roof. One can really tell the sudden change in the tune.
And what sort of a title for a song is this anyway - "Fur Elise"? Did he have a thing for hairy women...?