Thermite
Fe2O3(s) + 2 Al(s) → Al2O3(s) + 2 Fe(l)

65g thermite

65g thermite

Railroad welding

Mythbusters: Thermite vs steel

Mythbusters: 5000g Thermite vs ice

Mythbusters: 5000g Thermite vs ice

Mythbusters: 500,000g Thermite

Brainiac: Thermite vs liquid nitrogen