Boiling water, not only does it give a great cup of tea or coffee it is great for killing weeds or grass that is growing in places you don’t want it, mostly those cracks between pavers or joins in concrete paths.
If there is a patch that needs doing I usually fill the electric jug for my cup of tea, pour out what I need into a cup then the rest goes to the weeds or grass that should not be there. I use up the whole jug of water.
Our annoying place is in a path that is filled with gravel/washed rocks that has large stepping stone pavers, so when it’s noticed out comes the boiling water. You may need to do this a couple of days in a row there are often times roots underneath you don’t see.
I’m not sure what tv gardening show I saw this on but it was at least 10yrs ago and this method works well.
Be aware that for any weeds in grassed areas you will need to be as precise as possible with your water pouring as the boiling water will kill what it touches. I mostly use this method in non grassy areas.