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.

>>1
why physically desroy HDs?
way too bothersome and insecure...
all you need is strong encryption, and a medium that contains the key that you can destroy...
without the key the content of the disks is as good as random data.
an interesting question is if it suffices to just not tell the passphrase to your key...