My ball python did this a couple days ago as well. It was the weirdest sound I've ever heard in my entire life...sounded like a huge fart mixed with a gargly/puking sound. Really kind of horrifying, but kinda funny at the same time. I checked out her hide afterwards and found a ginormous fresh turd...must have felt great to let that one go lol. I also hopped on google as quickly as I could, and it seems perfectly normal. She seems really healthy so I'm not going to worry about it.