I’ve only ever heard “rausgeworfen” to mean thrown out, like kicking someone out of a physical establishment. Is this widely used for people getting fired from a job? Does it have a particular connotation in this setting?
Well, it looks very dynamic, it usually replaces the all too casual gefeuert
I also wonder, what is the difference between “kündigen”, “feuren” und “entlassen”.
entlassen is a neutral term used in formal contexts, not so much in (very) informal contexts. It doesn’t sound stiff or anything, there’s just no emotion attached to it.
kündigen is generally applicable in any context, be it formal or informal. It has a rather negative connotation and might imply that either the one dismissed did something wrong (if it is the former employer who speaks) or that the former employer did something wrong (if it is the dismissed person who is speaking).
feuern is colloquial.