Coolant level fluctuates too much

I have a problem with the coolant level from my car (Renault 1.5 dCI engine). It fluctuates too much.

I left home with the coolant level at the minimum mark. After approximately 10 minutes I stopped the car and the level was above the maximum mark with approximately 2-3 centimeters (~1 inch). I started the engine once again and drove for about 5 minutes. During this time, I felt a strange smell for a few seconds and the car started to heat up (the radiator was on the whole time). I stopped the car once again and the level of the coolant was below minimum mark. Overnight, the level of the coolant rose again to the minimum mark.

I have recently changed the entire coolant, the lid of the expansion tank, and the thermostat but the problem still persists. There is no foam / bubbles in the coolant, there is no white smoke, the power of the engine has not changed, the oil looks fine.

Does anyone know what may cause this issue?