ACQUAINTANCES STATED THAT THE STUDENT PILOT WAS VERY MOTIVATED IN THE PURSUIT OF HIS PRIVATE PILOT CERTIFICATE AND THAT, ON THE DAY OF THE ACCIDENT, HE WAS LOOKING FORWARD TO THIS FIRST SOLO FLIGHT. ACCORDING TO HIS INSTRUCTOR-PILOT, WHO ALSO WITNESSED THE ACCIDENT, THE STUDENT ACCOMPLISHED A SUCCESSFUL FIRST SOLO FLIGHT AND TAXIED BACK FOR FURTHER INSTRUCTIONS. AFTER A SHORT DEBRIEFING AND DISCUSSION WITH HIS INSTRUCTOR THE STUDENT TAXIED BACK TO THE RUNWAY AND MADE A NORMAL TAKE-OFF, CLIMBOUT, AND CLOSED-CIRCUIT TRAFFIC PATTERN. DURING FINAL APPROACH, OTHER WITNESSES STATED, THE AIRCRAFT BEGAN INCREASING THE PITCH ATTITUDE AND LOSING ALTITUDE WITHOUT ANY SUBSTANTIAL INPUT IN POWER. THE STUDENT SUDDENLY BROKE OFF THE APPROACH WHILE OVER THE RUNWAY THRESHOLD AND PROCEEDED IN AN ERRATIC, NOSE-HIGH, LEFT TURN MANEUVER BACK TO THE AIRPORT. HE CONTINUED IN THIS CONFIGURATION UNTIL THE AIRCRAFT APPEARED TO LOSE CONTROL IN A STALL-SPIN THEN PLUMMET, NOSE FIRST TO THE GROUND.