This trick, called "the traveling flame" or "flame dropping" is a quick fix for anyone who is feeling their inner pyromaniac getting restless. And it's a fun way to play around with those nice candles your family puts out for Thanksgiving.
Ever wonder why the smoke rises so high when a candle is extinguished, when there's almost no smoke while the flame is actually burning? It's because what you see rising from a recently extinguished candle isn't smoke, it's vaporized wax. When the flame is going, the wax gets burned up before it can escape. Some people are even able to tell their candles have been extinguished without looking because the scent of wax rises so sharply. It's how I know my Halloween pumpkin candles have gone out.
Because the wax is still in the air, and still in vapor form, it can still catch fire. All it needs is a spark. Grab a candle, light it and let it burn for a bit, and then blow it out. All the wax that was hot enough to vaporize rises up overhead. Touch a flaming match to it, and the flame will drop down again, and relight the candle. You can have some fun with this and try to light the candle with twirling smoke, or try different candles to see how far away you can light one from. (As long as they're supervised, this is a fun experiment to do with kids. Encourage your young firebugs, people.)
Via Science Off Center.