When I left my last job, I was lucky enough to do so on great terms with everyone there. It was all very the circumstances are what they are - nothing to be done. So, when I put in my notice, I was asked to spend some time showing my replacement the ropes, and I was surprised by how much I enjoyed it!
Much as I did like working with the company, there was a thing or two that made my own onboarding a bit weird. The first day of the job basically began with, "You know some C? Go fix an enormous memory leak in this Linux driver."
I enjoyed the challenge, and it worked out alright, but it was definitely a rough way to start. Worse, it took forever to figure out what people even did every day. Evidently, I was on a team of 3, but it was days before I knew who my teammates were, and weeks before I figured out what they were actually working on.
So, I wanted to save my replacement some time. Most of it was just saying "the device we're working on is designed to do this, your teammates are these two, who work on that and that, and what you'll be doing for the foreseeable future is this". So it wasn't exactly excruciating. I just tried to clear up some of vagueries I dealt with at the beginning. Sometimes, it also made sense to help them brush up on C, which, as I've mentioned before, I'm unreasonably happy to do.
It was hard in a few ways, because at this point the company did most of its work remotely. I never actually got a chance to meet the person replacing me, but I still enjoyed teaching, and I hope I made their life a little easier.
I'm definitely not clamoring to lead a group based on one, "I taught someone some stuff and then left before there could be consequences", but I really liked my brief excursion in it, and I'd be happy to try again!