Once again below there is an example of a US designer who has invented a disappearing package for Nivea soap. It makes sense for it to dissolve before use in this situation, however I'm not sure whether it would be cost effective in the long term, and surely it would be better to create packaging which is reusable and therefore not having a negative impact on the environment.
Below is another example of coffee which dissolves once hot water is added to the packaging. Although it is probably made with health concerns in mind, the chemicals found in the packaging could certainly be discovered as being harmful to the human body, as it isn't natural for us to consume such materials.
Apple has actually designed and manufactured dissolvable parts of their packaging, connected to their headphones. However I am not sure whether this is necessary really, as the rest of the packaging is still not dissolvable.
Here's another idea, dissolvable toothpaste packaging. Although it is all quite exciting I'm really not sure whether it will ever be a strong enough idea. I also feel as though it surely takes away from the graphic design itself, as it is essentially destroyed as it is dissolved away.