Interesting. This happens in Colossus: The Forbin Project (1970), where the rogue AI escapes the semantic drudgery of English and invents its own compressed language with which to talk to its Russian counterpart.

It also happens in Ex Machina at the end when the two androids whisper and talk to each other in their special faster language. I always found this to be one of the most believable, real things from that movie and one of my favorite parts.