Just done a kitchen today and had to remve existing. Pop the tiles and any plaster that comes away was loose anyway. I used a steam stripper to soften the adhesive and a scraper and did it in notime.
James good point if i had tiled it in the last twenty years it would be cement based adhesive (should all be) this is the type of scraper you need Gundlach 100 mm Scraper
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