You might already have seen this circuit: using an oscilloscope in X-Y mode it shows you the classic bipolar transistor IC - VCE characteristic. But how does it work? I'll try to answer this question with (almost) no math, to help you build a better analog circuits intuition.
Where I found this schematic: https://www.eddybergman.com/2017/06/simple-but-effective-transistor-curve.html