In very rare cases, popping a pimple in the so-called "danger triangle" can lead to facial paralysis, cavernous sinus thrombosis, brain infections/meningitis or brain abscess, and even death.
The "danger triangle" in the face is found in the area from the corners of the mouth to the bridge of the nose, including the nose and maxilla. The possibilities of having serious effect of popping pimples in the area is due to the fact that there is venous communication (via the ophthalmic veins between the facial vein and the cavernous sinus) and that the cavernous sinus lies within the cranial cavity, between layers of the meninges and is a major conduit of venous drainage from the brain.

It is very rare to have incident of this, and many seems not to believe but an incident from Philippines would give a strong evidence to this.This incident from Philippines involved a male teenager who developed brain tumor as big as a tennis ball. Fortunately, he was able to recover from it after a successful operation of removing the tumor.

Here is a video segment of GMA Kapusong Totoo featuring the recovery of the teen.

Thank you and have a profitable day ahead.