Ask HN: How to make sure that my explanation is being understood?

I feel like lot of times when I am explaining bit more complicated concept, the audience or the interviewer isn't grasping it. I would either start explaining too much or start rambling. How do you make sure your explanation is concise and clear without being either too superficial or quite elaborate? Also what would be the way to have some kind of implicit feedback when I am explaining it to someone so that I feel like they are understanding what I am talking about?