Yesterday I was watching my big burmese who was sitting pretty still, soaking in his pool, when all of the sudden his calm little soak turned into a jacuzzi session that lasted over a minute. I'm not talking a slow release either... at the risk of sounding a little immature, he machine-gunned it steadily with such force you not only heard all the bubbles popping on the surface, you could here it exiting the cloaca pretty loud under a good 8 inches of water. Although he blows bubbles a lot, that's the first time I've seen or heard them come out that end. (He often inhales real big, then sticks his head under water and blows it all out for some reason too) It's weird though, it's only one of my burms that likes to do it.
My retic gets real bloated at the base of his tail sometimes, but that typically only happens right before he's ready to defecate, I just assume that on a more slender body snake you're more likely to see the waste materials as they get close to release. A quick warm soak, or some handling usually loosens that up real quick.