What does the result is often fireworks means?

Fireworks are things which explode in a loud and chaotic (though pleasing of course) way. This phrase therefore is saying that the result of a particular action will be "explosive" in the sense that it will lead to trouble. It means that the consequences will often predictably be highly noticeable, unsubtle and quarrelsome (bad).

For example I might say that it will result in fireworks if I forget to buy my wife a birthday present!