Korean sentence ending that implies "Be careful! <X> might happen"?

Question

I would like to express "Be careful. < Something > might happen" in Korean.

Is there a sentence ending or any special construct in Korean grammar that implies this?

I am sorry if the question sounds a bit hard to understand, but I'm not really sure if what I want to express has a direct equivalent in English.

For example, let's take the sentence, "Be careful what you wish for, it might come true."

Is there a construct in Korean that succinctly expresses this feeling that something bad might happen?

EDIT 1:
(sample context in the hope of making the question a bit clearer)
(I am assuming 부수다 can be used to mean "to break a stick", though I'm not sure if I'm using that word correctly here)

Context:

A child is playing around with his pencil like a drumstick, I want to tell him (to stop because) "it might break"

Using the answer provided by Gaeguri as a reference, does it sound ok to say "부술라" ?

(or in case 부수다 means break as in glass shattering, just replace the word pencil with a glass cup in the above example )

Answer 1

One ending that expresses that is the ending -ㄹ라:

넘어질라! (Careful you don't fall!)

늦을라! (Careful, you're going to be late!)

다칠라! (Careful, you'll get hurt!)

I've heard this mostly with adults talking to children. I'm not sure if it would be OK to use in other situations.

Reference: 어미 조사 사전 (이희자 이종희 지음)

Regarding Edit 1:

Instead of 부수다, I think the verb 부러뜨리다 is better for a pencil:

부러뜨릴라!

For a glass, use 깨뜨리다:

깨뜨릴라!

Answer 2

You can express "~ 않게 ~ 해 (Do(Be) something not to do(be) something)." For example:

미끄러지지 않게 조심해 (Watch you steps not to slip)!

사고나지 않게 (or 않도록) 조심해서 운전해 (Drive safely not to have a traffic accident).

다른 사람들 방해하지 않게 (or 않도록) 조용히 해 (Be quiet not to bother others).

Answer 3

In addition to great answers, I would like to provide possible translations for "Be careful what you wish for, it might come true."

말 조심해. 진짜로 일어날지도 몰라.

Literally: Be careful what you say. It may really happen.

조심해. 말이 씨가 된다.

Literally: Be careful, your words will be seeds.

"말이 씨가 된다." is a proverb that means how words (not necessarily wishes) could be causes of reality.

Answer 4

Be careful of something.

그거 조심해(라).

Be careful that something is not gonna happen.

조심해(라). something 이 일어난다/일어날라/일어나겠다/일어나겠네/일어난디...etc.

Be careful not to make something happen.

조심해(라), something 이 일어나지 않도록/않게/않으려면/

조심해(라), something 이 안 일어나게/ 못 일어나게/ 안 일어나도록/ 못 일어나게

Basically, 조심해(라) comes after the other part, but often we use such inversion.

As participle clauses do, even no connection word between 조심해 and the other clause is allowed, but as leaving numerous ending like -나게,-나도록 and etc, the sentense can imply which kind of words are left out unlike participle clauses.