I've had a few students over my teaching career who won't stop talking. They can ramble on for upwards of 30 minutes or more, monopolizing my 1-on-1 time and class monitoring. It's exceptionally rude, but I can't seem to find a way to assertively break the "conversation" without appearing equally rude. In many cases, I don't even think the student is even aware of how long they've been rambling (and ironically, it's usually on-topic). Furthermore, once a student has done that to me, I tend to avoid them in future classes, for fear of it happening again. What is a good way to break away? What is a good way to stay engaged with the student's progress without getting caught in the rambling again?