mysqli_query($dbc, "SET NAMES 'utf8'");

<?php
header('Content-Type: text/html; charset=utf-8');
$dbc = mysqli_connect('localhost', 'root', 'root', 't_test') ; 
mysql_query("SET NAMES 'utf8'");
  $query = "INSERT INTO test (`test_test`) VALUES ('Поле для тестовой строки');";
  echo $query;
    $data = mysqli_query($dbc, $query) or die ('error01');
?>

character_set_client utf8mb4
character_set_connection utf8mb4
character_set_database utf8
character_set_filesystem binary
character_set_results utf8mb4
character_set_server latin1
character_set_system utf8
character_sets_dir /Applications/MAMP/Library/share/charsets/

mysql_query('SET NAMES utf8');