Sounds like a potentially bad thing. The easy problem would be something being clogged, maybe a thermostat not opening, a bad coolant/water mixture, or a radiator cap that isn't releasing pressure. But a bad problem would be a head gasket issue that's letting off exhaust into the coolant system and greatly over pressurizing it.
(it does make me wonder if the tiny cracks at the top of my radiator date back to when the head gasket went, and Toyota repaired it, now nearly 90k ago)