problems removing vinyl floor tiles

We're pulling up old vinyl/plastic floor tiles to make way for a new floor.
The existing tiles are in 3 rooms, all with concrete floors. One room they were on top of a lino sheet, so that was easy. The bathroom tiles had to be chipped off and have left stuff on the concrete. Dark brown (in places sticky) stuff, presumably a tar-based adhesive? Any ideas on how to get rid of these big patches?
The final room is the worst - we've not yet removed the tiles, because there's something underneath them, which is stuck hard to the concrete. Whatever it is it seems crumbly/fibrous when chipped at.
Not sure what it is - maybe a layer of levelling compound ?, or it may be some kind damp membrane ? - or it maybe be some kind of underlay/floor - in which case I'm a bit worried it might be asbestos (area in question built in 1982). Its about 2mm thick, greyish/brownish, with the dark adhesive on top.
I've uploaded pictures of them, if its any help !
pic1 - the adhesive stuff:
pic2 - the thick stuff:
any advice / info much appreciated.
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