The pilot departed the local airport with intent of practicing traffic pattern work and basic flight maneuvers. After 3 touch and go maneuvers, the pilot departed the traffic pattern and flew the airplane to the designated practice area. After performing a couple 360-degrees turns and slow flight, the pilot attempted a power-off stall. In order to prepare for the power-off stall, the pilot retarded the throttle and applied the carburetor heat. During the recovery of the power-off stall, the pilot "rapidly" applied engine power, closed the carburetor heat, and the engine lost power. The pilot attempted to restart the engine, however, the restart was unsuccessful. The pilot elected to perform an emergency off-airport landing. During the forced landing to a field, the pilot landed the airplane in a downwind direction and was high on the final approach. The pilot stated that he should have slipped the airplane during the approach which would have allowed for "use of more of the chosen field...a longer flare and a lighter touchdown at a lower airspeed." The airplane impact crops and terrain and came to rest on its nose. Examination of the airplane revealed the firewall was buckled. According to a designated pilot examiner, the rapid throttle application can result in engine flooding and subsequent engine failure.