Ok  so I  was  dropping a  riding mower off at   a  customers  house. Me   and the  dude    were  just shooting  the  breeze   when this neighbors  tree   and   shrubs  just burst into fire  out of  freaking  no  where! there is  no mulch under the  bushes, just dirt. No electrical  cores,  matches, embers  or   accelerates. it just randomly went  FWOMP!