In this talk we will present our most recent numerical and observational results on the formation, evolution, and X-ray emission from hot bubbles in nebulae around evolved stars. Our studies include hot bubbles around massive and low-mass stars, e.g., Wolf-Rayet nebulae and planetary nebulae. Our results show that the diffuse X-ray emission from these hot bubbles is a dynamic process that involves mixing of nebular material into the hot bubble due to hydrodynamical instabilities, photoevaporation, thermal conduction, and dust cooling. The formation of these hot bubbles is governed by the evolution of the stellar wind parameters, and its properties can be used to study stellar evolution.