Last year, I was having trouble keeping the humidity up in my apartment when I started using my gas wall heater...it baked my entire place bone dry...
I had an adult male
Suriname boa, and a large adult female ball, that both did something very similar...
The sound was bizzare, like explosive farting or loud beer/soda belching, and their enitre body jerked forcefully when they did it...both had their mouths slightly open as well. I'm guessing it was sort of like a dry heave, as neither regurged anything, not even fluid...
Once I got the humidity issue taken care of, it never happened again. Both were healthy after that, and displayed no problems at all.
What they are actually doing, I have no idea...but I strongly believe the low humidity caused the behavior...
