flash point

noun3

1. •
   The lowest temperature at which a liquid can form an ignitable mixture in air near the surface of the liquid.

   • The whole cursed corporation ought to be rooted out and drowned in its own incombustible product. What is the flash point of this condemned coal oil anyway? — 1916
2. •
   The critical stage in some process, event, or situation at which action, change, or violence occurs

   • The attack could prove the flashpoint for war.
3. •
   (figurative) A hotspot; a dangerous place of violent political unrest.