"Chłopcy myślą o zupie."

Translation: The boys are thinking about the soup.

[Draugtaur]

ah, boys will be boys

[HelbentForleder]

I believe they actually prefer to think about cabbages and beetroots. :?)

[Vengir]

Or about blue almonds.

[aGABT31]

They are thinking about soup because their mum makes them share a single mug of tea and they are dehydrated . . .

[RadhaTereska]

Czy nie myślą na prawde o piwie?

[Vengir]

"Naprawdę" is a single word.

[RadhaTereska]

thanks

[Yola448704]

"Heavenly", coming from the proverbial sky... a dream.

Chłopcy myślą/marzą o niebieskich migdałach (idiom) -
(idiomatic phrase) Boys are daydreaming/ Boys dream

[Vengir]

True. But unless you dig into the etymology of the idiom, the first connotation is "blue". These days in that meaning we would say "niebiański".

[woleks]

Why not "The boys are thinking about a soup"?

[Jellei]

Seems possible, added.

[Yola448704]

No article "a" before uncountable noun...
You can say "The boys are thinking about soup/ some soup/ the soup", or:

"The boys are thinking about a bowl of soup - Chłopcy myślą o talerzu zupy