I just want to remind people that vomiting is a specific bodily process that expels the stomach contents through the mouth and/or nose. Not everything that results in stomach contents coming up and/or out is vomiting. There is also:

1) burping - where air/gas (and occasionally small bits of fluid or solid stomach content) come up from the stomach
2) rumination - what we're talking about here ("vurping") where a small bit of stomach content comes up to the throat. This happens not by the muscular force of vomiting but by the wave action (peristalsis) of the muscles of the esophagus.

Neither burping nor rumination can expel solid matter from the body. In order for that to happen, you have to bring the stuff from your throat to your mouth with your tongue and then spit it out. So when something comes up by burping or rumination, you have a choice what to do with it: swallow it, chew it and swallow it, chew it and spit it out, spit it out. When you vomit, you don't have a choice. It just comes out.

Doug