Astronomers have long observed hot gas bubbles in our Milky Way. These formations are a few hundred light-years across and give the galaxy a texture akin to that of Swiss cheese. Such bubbles can also be found in other galaxies such as the Large Magellanic Cloud. Ironically, observing the bubble closest to us turns out to be particularly difficult. Because we are in the middle of it - close to the center.
The gas in this local bubble is up to a million degrees, but only about