It's not really an explosion. It's typically the thin abdominal area becoming weak and bursting as the natural part of decay. It's happened to me and it's not pretty and the smell you never forget.
Exactly. the freezing, thawing, freezing, thawing cycle will weaken the skin over their intestines.
And no, it's not like a fire cracker exploding...it's just their guts start oozing out and the smell is one of the worst things I've ever smelled. Very unpleasant.