Someone linked me to these amazing sounds of ice cracking, which sound a hell of a lot like lasers from Star Wars. Go click and listen, they're amazing.
I don't know the details of the physics, except inasmuch as I understand that it relates to the speed that the different frequencies of sound travel through the medium of ice. So the high frequencies travel faster, the low slower, and that results in these huge glissandi (aka doo! doo! laser zaps).
