While it may not carry some of the connotations that "ballooning" (growing rapidly as if you were inflating a balloon) or "spiraling" (show a continuous and dramatic increase) have, the DRAE includes "sobrecrecer"
Exceder en crecimiento o crecer excesivamente.
As an advantage, it is one word.
[...] la sobrecrecida deuda pública
[...] la sobrecreciente deuda pública