It would be nice if someone posted pictures before and after the heating... so you could see the difference...
Unfortunately i havent a camera (nor weed) so i cant help very much... but i can say that the weed, initially clear green, becomes yellowish, or even slight brownish, dry and crunchy. It seems like toasted weed. You can also heat it in the microwave (if you have one)... the range of time for microwaving is great... some people says that 15 seconds are enough, and some people say that 2 minutes are enough... i would suggest 1 minute... anyway, good luck!