Constant overheating?

After starting the car, within a few minutes the temperature gauge is about 2/3 the way up. After driving it for a short period the gauge will rise slightly to just before the red line. From outside the car after I turn it off it smells like something is burning, like an engine smells like when running without oil, and I can hear a loud hissing sound for a couple minutes until it slowly goes away then stops. I have replaced the radiator, water pump, and thermostat (several times) already and no mechanic is able to come up with a solution to the overheating. If I drive for too long something blows, and the car temperature goes beyond the limit line and it completely stops running. This happened before which is why I replaced those parts. It ran after that but still gets hot. Almost everything else under the hood has also been replaced recently. The hoses are swollen, and I was told they need to be replaced but the mechanic won't do it without charging me to replace the thermostat first, stating that it's a starting point to narrowing down the problem.