Burning propellant ejected
Rocket used was an Estes V-2 with the nose cone modified by cutting off the bottom cone, leaving just the nose and shoulder which was partially filled with epoxy to provide nose weight and shock cord retention.
Event left the empty motor casing intact without a nozzle in the rocket. The majority of the propellant appeared to fire up inside the rocket, burning sections of the nylon parachute and up into the nose cone where it burned through the elastic shock cord and melted the lower half of the nose cone.
Prior to the event the motor had been stored in an ammo can with other Estes motors without its original packaging for about a year. Suspect that at some point the motor developed a crack in the propellant due to being jostled around in the can over time.