Methane bubbles is a well-known demonstration that is rightly popular.
Many schools, however, do not have access to mains gas 9methane, and bottles gas (LPG) is not suitable for the carrying out the experiment safely being denser, hotter and slower burning.
An alternative is to use bubbles of hydrogen. This can either come from a cylinder or be generated chemically. The burning of the bubbles is done in the same way as burning methane bubbles
Hydrogen Bubbles – Teacher
Hydrogen Bubbles – Risk Assessment