Boun Bang Fai Festival of Laos

One part of the Vixakha Bouxa festival is called Boun Bang Fai, or the Festival of the Rockets. As this is during the hottest and driest season of the year, large homemade rockets are launched into the sky in an attempt to convince the celestial beings to send down rain. Traditionally, Buddhist monks made the rockets out of hollow bamboo tubes filled with gunpowder (among other things). Nowadays, lay people make the bang fai more like fireworks and hold competitions for the highest, fastest and most colorful rockets. The event takes on both sides of the Mekhong River border between Thailand and the Lao Peoples Democratic Republic, and sometimes teams from the neighbouring countries will compete against each other. Tourists travel long distances to witness this now popular event.

Source:en.wikipedia.org