I've read on this forum that people sometimes get an audible sound when they flush with or Epson salts. I get wheezing noises about 15 minutes after I swallow the oo/lj potion. Sometimes I feel movement but there is nothing to see the next day and when I expelled my mammoth stone I felt nothing.
I suppose you've got to look at the plumbing which will slightly different in all of us just like every other characteristic. The flow of bile is controlled by muscle with a reflex triggered by the olive oil. Just like kitchen taps (faucets) being turn on and of make load noises in some houses and not others I guess bile systems are the same. You've also got olive oil moving from the stomach to the duodenum. That’s a lot of things going on.
I would just consider the "POP" to be a side issue and not let it interfere with you quest.