tinderbox

noun3

1. •
   (historical) A small container containing flint, steel, and tinder (dry, finely-divided fibrous matter), once used to help kindle a fire.

   • Just bring me the old tinderbox that my grandmother forgot the last time she went down there. — 2007
2. •
   A place that is so dry and hot that there is danger of fire.

   • And then came the night that made America famous / Was it carelessness or someone's sick idea of a joke? / In the tinderbox trap that we hippies lived in, someone struck a spark — 1974
3. •
   (figurative) A potentially dangerous situation.

   • This act was the "match that ignited the great tinderbox of fuel" that had been building for years between many of the countries in Europe. — 2010