I can understand the construction like the following with vanish and disappear.
- The money vanished from my wallet.
- Money seems to vanish into a black hole.
- A strange light appeared and vanished into the darkness again.
- The sun disappeared behind a cloud.
- His sudden disappearance is very worrying.
In the following sentence,
All the chocolates vanished away in no time at all.
what if the adverb away used with the verb vanished is dropped? It appears to be redundant.
Both of the idiomatic phrases vanish into thing air and disappear without trace appear to mean "vanish all of a sudden in a way that seems impossible or in a way that cannot be explained or at least difficult to explain", such as
- When the hunter looked again, the bear had already vanished into thin air.
- The plane disappeared without trace and no survivors were ever found.
How much does it make a difference, if the first sentence is given "disappeared without trace" and the second one is given "vanished into thin air"?
Moreover, the indefinite article a is quite less frequently seen with disappear without trace such as disappear without a trace. Does the article a have its own meaning in some contexts or it's just optional?