Water molecules are dipolar molecules. This means that they organise their electrons in such a way as to make one side of the molecule positively charged and the other side negatively charged....
My microwave's manual clearly states that the bulb is NOT a user serviceable item. Your oven may be the same. Check your manual or contact the manufacturer. They probably have a website.
If it turns on by itself, then yes, it very well might! Our microwave kept turning itself on for 7 minutes during the night. Luckily, someone would usually here it and unplug it. One time my friend...