I've only heard of something similar to that situation before back when I worked at a pathology lab. I've never heard of it "exploding" to that extent but it has happened someone has a bowl movement, the fecies expands in the water thus mixed with the natural gases from your body. Causing it to break apart but not explode. Sounds like you've had some gaseous experiences... watch what you're eating and don't drink so much carbonated drinks. Take it easy....
...did you lick your shit off your face? hehe