Why is my coolant boiling in the reservoir And my car isn't over heating?

What is your question?

I have a 2004 Volvo XC90 turbo. The first sign was low coolant. I checked and it was boiling. Then before I could get home it said low coolant stop engine. Again I checked, it was boiling. Then the antifreeze starts leaking and I was told the radiator had a small hole in it. Now my car never over heats BUT the coolant in the reservoir is HOT!! When I took it to the shop,and I explained how the coolant is boiling hot.He said it wasn't a good sign. I'm a single female and I would kind of like to know what the problem is so I won't end up paying for things that isn't/ wasn't really needed. Please help!!!!!