That would be unusual and if it did happen the noise would be quite loud as you would have springs and everything rattling around along with a loss of breaking as the cylinders would pop out, I think you can totally disreguard this as a likely problem.I hope for a broken brake shoe !
The shhh shhh sound, sounds like a possible brake shoe rubbing as if it is not releasing properly, Willie had a similar problem but I dont know what sounds he was getting, and he had to replace the wheel cylinders as the rubbers had swollen (if I remember correctly)