I think it'll keep the "potency" inside the dome (bong-style) for a few minutes... 60 minutes tops... I THINK.

As to burning it down to a popcorn... well, when I did vape, I didn't push it... if it stopped producing vapor, I tossed the weed.

But if you want to get every last bit of THC out, roll a joint... I'm sure you'll get 0.04% higher.