Episode 442 - Just what is a metal anyway

Just what is a metal anyway? It can be hard to classify things, no matter what you do there's always exceptions to the rules. Chemists, Physicists and Astrophysicists have wildly differing opinions on what a metal is. Although there is disagreement about what makes a metal, can you find new exceptions? What needs to happen to turn water into a metal? Can pure water be made to conduct electricity without needing a Jupiter sized planet? How do you turn water into a golden, shimmering, conducting metal? 
References:

1. Philip E. Mason, H. Christian Schewe, Tillmann Buttersack, Vojtech Kostal, Marco Vitek, Ryan S. McMullen, Hebatallah Ali, Florian Trinter, Chin Lee, Daniel M. Neumark, Stephan Thürmer, Robert Seidel, Bernd Winter, Stephen E. Bradforth, Pavel Jungwirth. Spectroscopic evidence for a gold-coloured metallic water solution. Nature, 2021; 595 (7869): 673 DOI: 10.1038/s41586-021-03646-5