I also felt that several times and not to long ago like a few mins ago it happen to me again and it scared me that it made me jump idk what it is either but I am wondering..
oh i had that all the time it was the babies joints popping
oh great shes not even born yet and she has my popping joints lol poor thing shes in for a long road
you know my son is 4 months and hasnt popped any since being inside lol mine pop all the time too