It seems pretty clear from these symptoms that the engine is massively overheating. That explains the boiling water in the overflow tank which will be dirty mainly form rusty deposits within the engine’s cooling system. The question then becomes what’s causing the overheating.

There are lots of reasons for an engine to overheat, including low coolant level, a blocked radiator, collapsed radiator hose, failed head gasket, incorrect ignition timing, poor fuel mixture, a damaged or missing fan shroud, slipping fan belt, worn water pump and many, many more. But a good mechanic should be able to assess the situation, do a few quick tests and determine the root cause of the overheating, then you can move forward on a fix, knowing that you’re tackling the correct issue.

The other piece of advice is to not drive the car until it’s fixed. Continuing to drive with an overheating engine is a great way to destroy the engine completely. At that point you need a new engine or a new car.