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"

Sobrecrecer

 

Exceder en crecimiento o crecer excesivamente.

As an advantage, it is one word.

[...] la sobrecrecida deuda pública

 

[...] la sobrecreciente deuda pública

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"

Sobrecrecer

Exceder en crecimiento o crecer excesivamente.

As an advantage, it is one word.

[...] la sobrecrecida deuda pública

[...] la sobrecreciente deuda pública

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"

Sobrecrecer

Exceder en crecimiento o crecer excesivamente.

As an advantage, it is one word.

[...] la sobrecrecida deuda pública

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"

Sobrecrecer

Exceder en crecimiento o crecer excesivamente.

As an advantage, it is one word.

[...] la sobrecrecida deuda pública

[...] la sobrecreciente deuda pública