a burp laced with a little vomit, usually occurs when you've had one too many and it has become difficult to distinguish between the two

A burp which results in the regurgitation of a small amount of solid material into your mouth (not necessarily vomit, but more than reflux).

to burp up vomit that burns in your throat.

When a person burps and slightly vomits in their mouth while doing so.

When you vomit and burp at the same time.