I had always thought 打破沙盤問到底 means: "one is so insistent on asking a question, it is like searching so hard for something in the pot that one breaks the pot." It does not really sound right but I could not come up with a better explanation.
Until a few days ago. It turned out the saying is actually 打破沙盤璺到底. 璺 sounds like 問 but means “crack”, rather than “ask”. So the saying actually means: "... it is like a crack in the pot extending all the way to the bottom when the pot is broken." Now that makes more sense, doesn’t it?
Whom did I learn this from? My youngest daughter. So I learn something new everyday. Even from someone decades younger than I am.
Chinese is really a fascinating language. And never underestimate young people.