A fragmenting nozzle system includes a first nozzle at least partially disposed within a second nozzle. The first nozzle includes an ablative shell, a syntactic foam support disposed between the ablative shell and the second nozzle, and an ignition system disposed at least partially within the syntactic foam support. For example, the ignition system is operable to generate a controlled-energy deflagration pressure wave that fragments the first nozzle but not the second nozzle.