How to explode a hard drive

I know this isn't strictly tech, but I felt it's the best place for it.

People talk (on 4chan and such places) of raids by the police on their house to recover hard drives due to suspicions of CP or of pirated content.
I was wondering if anyone knew of a case where someone actually managed to destroy their Hard Drive, either remotley or before anyone could get to it, or any stories of the sort.
Could it hypothetically be fitted with some sort of... remote water filling thing?
Post anything relevant please.

Wont't help against party van if they caught you at surprise, but opening up your HD and burning insides GUARANTEES that's it's 100% unrecoverable. Can't recover anything from melted mass plastic. I don't see much point doing this though, if you know party van is coming you can hide your HDs at your friend's or relative's house.