Burning?

Something strange has been happening at our house & it's really quite concerning! Every once in a while we can smell some thing burning. We originally thought it was coming from a ceiling fan in the master bedroom ... there were wires that had been burned, so that *was* a problem. How ever ... tonight, we had the heater on & the washer and dryer going ... all the sudden a burning smell was very obvious. We shut down everything & the smell went away. It hasn't happened since my husband got home ... ugh ... I hate it when that happens!!! Hopefully we'll figure out what it is quickly & every one will continue to be safe!!!