This is a tip I was reminded of during our power outage. Freezing (or cooling) wax hardens it and makes it easier to remove.
I primarily use this idea to get the melted ends of votive candles out of votive holders. Just put the glass candle holder in the freezer for a little while. When you remove it, give it a light tap on a hard surface and the wax in the bottom should come loose.
I have often read that this idea is also useful for removing wax from a tablecloth. I haven’t had that problem in a long time, so it’s been a while since I’ve done it, but if you rub an ice cube on the spilled wax, it hardens the wax and makes it easier to remove.