Thank you. I was freaking out. Isn't this what they call a stream of consciousness?

I think if this experience is related to having ADHD, the part that is relevant is the lack of ability to acknowledge that you've made a jump at all. In the example it's a perfectly valid train of thought, but I'd expect an average person to make an effort to bring the other up to speed. Because most people generally expect to continue conversation in the same topic, you spend mental effort trying to keep tethered to that topic and have to share that rope with the other person.