2k7G35s

I was almost home coming down the street and had to get throw one last snow pile, so I accelerated through it, but towards the end I heard this POP! sound come from the back end(passenger side ?), I have 300 lbs of sand in the trunk which has helps tremendously(haven't gotten stuck since I added it), was it the suspension popping from the weight or the viscous fluid popping or what ????