if this was me having this dream the fire would not mean anything other than I over cooked what ever was in the microwave or the microwave had a short in one of its components or the microwave was just old and my dream was telling me time to get a new one before afire does break out.

my point there are many ways to interpret dreams but ultimately only you can interpret your own dreams and what they mean because only you know how and why you had that dream..

dreams come from our emotions, memories, feelings and sometimes are just a mish mash of things that fall together but do not have any ulterior meanings.

my suggestion is contact your or a treatment provider who can help you figure out what your state of mind, disorders, medical issues, memories, emotions and all are. in this way you will figure out if that dream actually has an ulterior motive\interpretation for you or not.