Curious question.

[kevin pedro]

How can I tell if the wax of my lava lamp is burned or not? 

[Gwen Williams]

The most obvious sign is that it turns black and stops flowing.

[Samantha Gregory]

Yeah if it is stuck to the top and sides the bulb could be to hot

[Astralav]

If you mean "shot" by "burned", well, if your lava only make some small nuts size blob rapidely, it's shot /dead and couldn't be fixed.

[Samantha Gregory]

If it's sticking to the side try a few drops of miracle bubbles which is bubble blowing liquid and it should stop sticking

[Brad]

hi kevin - if you would post the information from the cap of the globe and some photos of the problem, it will help us help you!

[Samantha Gregory]

Great idea Brad

[Metallica Man Trevor]

If its stuck to the bottom of the globe.

[Dr. WHAT?!]

Quick over heating with no flow or too much flow (stays at the top), runny looking wax with lots of bubbles (takes less then 5 minutes to spike when you turn the lamp on) are all usually a good signs you lamp is done for. Pics definitely help.