> Any thoughts?

An infra-red laser pointer thermometer will cost you $40 at the most -
buy one and point it at the metal parts around the thermostat (near
water-pump).  The farm is worth it and exotic coolant hoses are more
expensive than that.

Does the radiator get hot?  As suggested, coolant level sensor - but
how fast did the temp shoot up?  From nothing/normal to pegged in 5
seconds is likely a coolant sensor fault - or perhaps the engine is on
fire... actually, no, it would take longer to boil coolant and the
smoke is a dead give away.

Tom