Replace both hoses while you are back there. If one went, the other will soon. I had exactly the same situation occur, 5 miles from home, steam out of the back of the engine.
I would check the tank and fill neck for a crack if you are not over filling it. Our system uses a pressure chamber. If the tank water level is low, the system pressure will also lower at the same temperature. Only way to over pressure it,is to either over fill or over heat.
Mine had a micro crack at my neck which would seep slightly. Replaced the tank, which is a common occurrence.
__________________
A common mistake that people make when trying to design something completely foolproof is to underestimate the ingenuity of complete fools. -Douglas Adams
2003 X5 4.6is Estoril Blue
2005 Infiniti G35X
1972 Datsun 240Z
1991 Isuzu Impulse XS Sold
1972 Fiat 850 Spyder Donated
1972 Datsun 240Z Sold
1972 Datsun 510 Sold