ok, now I have done this, and if you give it some thought it really makes sense. Cannabis produces resin for 2 main reasons, first to catch any and all male pollen that is floating around to create seeds, next to protect itself from the burning late summer sun.
With that said, if you raise the temps and cut some water then the plant thinks that is ready to die and in a last attempt to get pollenized it packs on as much thc as possible.
I do agree with ganja and hick though that it is never a good idea to stress you plants, but I only do this for about 4 days before harvest. This also helps give a shorter drying period as the moisture level in the actual plants goes down.
but this is only what I have found to work for me, with my strain, which is 100% indica, and it naturally use to hot dry summers