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.

Just so you guys know, it's AGAINST US LAW to do stuff like this. IE if you are a suspect of CP and the key to your encryption has been destroyed but they have your computer you can still get into deep trouble. It just so happens that there was a pedo in my hometown. He put a huge electronic magnet in his front door that is always on and when the cops came all of the cool stuff they took out of his house was fried, I assume. But he got many, many years in the state pen.