As far as popping goes, if you preburn the mesh before putting it in the machine (as you should)  you may notice some, which is apparently just a result of thermal expansion.  Just avoid applying direct flame, but don't worry too much if you accidentally do.  If you have to take more than one toke to get the desired effect, I strongly suggest you do.  You shouldn't need any more than four, but I think there's always going to be some amount left; it'll probably be an active amount since spice seems to be active in as low as 2mg.  I don't think most machines will vaporize the left-overs too well, but I know mine will.