It's easy to make explosive hydrogen gas using only household chemicals. For this experiment all you'll need is sodium carbonate (made earlier or just use washing soda), water and aluminium foil. For equipment you'll need a large plastic container and a jar that can fit in it.
See diagram below for explanation.
Set up the jar and tub diagram as shown using warm water. When ready, dissolve in a generous amount of sodium carbonate without letting air into the upturned jar. About 5 to 6 teaspoons should be enough. When dissolved, scrunch up a few balls on aluminium foil and place them under the jar. Bubbles of hydrogen will start to form and fill up the jar.
When it is about 3 thirds full, pull out your jar and place a lid on it. There needs to be about 1 third air in your jar for the best explosion. The explosion isn't terribly impressive and be quite safely ignited with only a match at arms length. When you want to ignite your hydrogen, prepare a match, unscrew the lid and drop it in (be quick before the gas escapes). You'll notice water vapour condensing in the jar, as hydrogen burns with oxygen to make water.
The explosion is more of a fast burn but will guarantee to make younger siblings scream and demand more.