vw beetle overheating

I have a 2003 Beetle 1.8 that is still over heating. I changed the water pump, radiator, thermostat flushed it. So after I changed all that. The light came on that said the vehicle was overheating. When I stopped I noticed the expansion tank was boiling. I don’t know what that means. Any advice...

This is my first post so please bare with me... My wife has a 2003 vw beetle gls convertible. She recently had it overheat on her while 200 miles from the house. I met up with her and found that the coolant flange on the side of the engine was melted... I replaced that, it held water, but had...