I have clicking in my hips, pubic area, and back. Basically all the bones in the region. Like if I roll over in bed, my pubic bones make a popping sound. If that's where your sound is coming from, it's normal. Things just get loose and "clicky" near the end. The only pop I've ever had coming from my actual belly was when my water broke with DD - and it was loud and VERY apparent what that was, 'cause gobs of water then poured out, LOL!