The Greek phrase translated here as “Jesus answered and said” is (in Textus Receptus) a combination of “ἀποκριθεὶς” ("answering") and “εἶπεν” ("said") separated by “ὁ Ἰησοῦς” ("Jesus"), so together it is “ἀποκριθεὶς ὁ Ἰησοῦς εἶπεν” ("answering Jesus said").
There are quite a few places with “ἀποκριθεὶς” and “εἶπεν”, in which the speaker is not answering any specific question, but rather saying something as a response to what he sees happening. Here are some examples:
1) The speaker (Jesus) is responding to Pharisees’ thoughts:
And the scribes and the Pharisees began to reason, saying, Who is this
which speaketh blasphemies? Who can forgive sins, but God alone? But
when Jesus perceived their thoughts, he answering said unto them, What
reason ye in your hearts? (Luke 5:21-22)
Now when the Pharisee which had bidden him saw [it], he spake within
himself, saying, This man, if he were a prophet, would have known who
and what manner of woman [this is] that toucheth him: for she is a
sinner. And Jesus answering said unto him, Simon, I have somewhat to
say unto thee. And he saith, Master, say on (Luke 7:39-40)
2) The speaker (apostle Peter) is responding to what he sees happening on the mount of transfiguration:
And, behold, there appeared unto them Moses and Elias talking with
him. Then answered Peter, and said unto Jesus, Lord, it is good for us
to be here: if thou wilt, let us make here three tabernacles; one for
thee, and one for Moses, and one for Elias (Matthew 17:3-4)
3) The speakers (scribes) are responding approvingly to Jesus’ teaching concerning resurrection:
For he is not a God of the dead, but of the living: for all live unto
him. Then certain of the scribes answering said, Master, thou hast
well said (Luke 20:38-39)
(note that in the example above the scribes were just some of the crowd and Jesus was not talking to them directly; in fact, as the verse 27 shows, He was talking to the Sadducees)
4) The speaker (angel) is responding to Mary Magdalene, the other Mary and the tomb keepers’ fear caused by his appearance:
And for fear of him the keepers did shake, and became as dead [men].
And the angel answered and said unto the women, Fear not ye: for I
know that ye seek Jesus, which was crucified. (Matthew 28:4,5)
5) The speaker (one of the 24 elders around the throne) is in fact not even responding to anything, but rather starts a conversation with apostle John by asking him a question:
Saying, Amen: Blessing, and glory, and wisdom, and thanksgiving, and
honour, and power, and might, [be] unto our God for ever and ever.
Amen. And one of the elders answered, saying unto me, What are these
which are arrayed in white robes? and whence came they? (Revelation
So, keeping all these cases in mind, I think we’ll be safe to assume that in Matthew 11:25 Jesus was not answering anybody’s question in particular, but was simply responding to what He saw, and the response was His immediate praise to the Father.