Burning sulphur pours from the side of the Kawah Ijen volcano, which is part of the Ijen volcano complex in East Java, Indonesia. While the sulhpur appears bright red during the day, at night it gives off an eerie blue light with flames that can reach up to five feet in height (1.5 meters). Of course, the key is that it "appears" one color during the day and another during the night. It's really just easier to see the blue color when it is dark.
This lava turns the rocky slopes into a hot wasteland (it's at least 239 degrees Fahrenheit or 115 degrees Celsius at any given time). Oh, it also turns the area into a highly toxic environment. See some amazing videos of this in action below.