When making dishes with tinned tomatoes etc, it is good practice to rinse these out with water to get the remaining contents out. Sometimes, to save on washing up I use hot or boiling water instead so I can then dissolve a stock cube etc. In the liquid. Having read that tins are coated and bottles can leach chemicals, is this a safe practice? 
Tinned food is already cooked above the temperature of boiling water (Canned Food Alliance).  So with tins it's not a problem.  Rinsing with something acidic or very salty may not be a good idea if the container didn't hold comparable food in the first place, as it may cause corrosion (that's why tomato tins are lined, to stop the acid attacking the metal). Tetrapak-style cartons use a different approach, Aseptic packaging in which sterilised or pasteurised food is packed cold into sterilised containers in a sterile environment.  However the inner layers are polyethylene which can be used up to 120°C briefly and 110°C for longer.  So they're OK too.  There may be exceptions to this, so you may wish to avoid using boiling water just in case. Plastic bottles are different - many are PET (Polyethylene Terephthalate) which has a far lower maximum temperature.  If you pour boiling water into a PET bottle, you're quite likely to leach stuff out into the water, and you may even end up with boiling water on your feet as the container softens so much it could break.  Use cold water for rinsing plastic bottles (not all are PET, but it's easier to just use cold for all of them; some others also soften enough to be awkward to handle, which you don't want with boiling water) 