1999 Range Rover Vehicle keeps blowing the heater return ho

Hi my tuck keeps blowing the heater return hose. I replaced the thermostat few months ago. A couple of weeks ago it blew the heater return hose, these are two identical hoses on top of the engine going towards the passenger compartment. yesterday truck would start to heat up then couple of minutes later it would go back to normal. It did that for few minutes and then it blew up the hose which was not replace and is next to the one I replaced. any ideas?1