[Lucky]

It could very well be the air-oil separator (AOS). A fancy name for what historically has been called a PCV (positive crankcase vent or valve) on lesser vehicles.

It's a known problem on Boxsters, but once replaced with the updated part it ceases to be a problem.

When they fail many folks think the very impressive plume of smoke means the engine blew... not the case.

I hope this is your car's problem as it is a non-event in the grand scheme of Boxster ownership.

Good luck.