Why does Python keep popping up and occupying my CPU?

Python with a capital P is the launcher app, found at /System/Library/Frameworks/Python.framework/Versions/2.7/Resources/Python.app

This is used when a python script uses MacOS GUI components, such as creating a window, dialog or file panel.

It's likely that some process is calling a python script to do something. What that is and why it's using so much CPU is unclear without more analysis. In Activity Monitor, you can see what files the process is using, which would be a place to start.