1. Go to Preferences -> Editor -> Code Completion -> Language: HTML and disable the following:
Equals-sign (=) Keypress After Attribute Name Autocompletes Quote Set
Quote-Mark(") Keypress After Attribute Name Autocompletes Closing Quote
2. Create an HTML file
3. Create a div element and type an attribute like id="", you will get id="""
Added a video on Vimeo demonstrating the behavior.
Not reproducible on 7.3 dev build. Many fixes have been done to this area recently, see Bug 212692 - single quotes autocompletion incorrect