Set a stove top burner to high. Put the oil in a large uncoated metal mixing bowl then add the salt and the chili powder. Once the oil is very hot add popcorn.
Cover and seal the top with a sheet of aluminum foil, then using scissors or a fork, poke a few holes in the top for the steam to escape.
Using oven mitts, or a pair of tongs if it is gets too hot, set it on the burner. With a back and forth motion, slide the mixing bowl over the burner quickly enough to keep the popcorn moving. You can hear the popcorn sliding around if you are doing it correctly. After a minute or two it will start popping and you really have to get it moving so the popcorn does not burn.
Once the popping slows to just a few pops per second remove from heat and tear the foil off the top. Transfer to a cool bowl and dig in.