Exploding loo's were common in the older conventional submarines.

I was on the old Porpoise and Oberon class and the loo ( known as a head in the RN) had to be flushed to sea using a complex series of operations where you closed the lid, and operated a number of valves, this forced water at pressure into the bowl, forcing the contents overboard via a one way valve.

We used to wait in anticipation as a new trainee used the heads for the first time dived. You would often hear them fumbling with the valves and getting it wrong, this was followed by a muffled whumpf and a cry of 'Oh shit' as the unlucky depositor got his own back.

Needless to say the unlucky person had few people who would stand near him as he made his way to change clothes.